First the reason it works great as incubator is because the door are closed so it completely insulate the egg boxes, in your case the doors would need to be left open for airflow, so already you would lose some of the insulating benefits, and between the money spent and time sent and the fact that you will only be able to fit small tubs (which means forget about adult females) I am not sure you plan is really worth it compare to buying an enclosed rack or even building one.